This invention relates to an automatic masking device for use in a printer in which an original picture is projected through a focusing lens onto a photosensitive material such as a film, a plate, or the like, mounted on a photosensitive material holder.
When a plurality of original pictures are printed one by one onto a photosensitive film according to the desired rayout by using a grouping camera or a projector, one picture is exposed, while the surface of the photosensitive film except the corresponding portion to the one picture is masked by a masking device.
When the masking is carried out, masking plates are preferably contacted with the photosensitive film. However, in a conventional masking device, the masking plates are separated from the film so as not to damage the surface of the film. Accordingly, in this case, when the angle of view is large, a considerable error between the opening distance between the masking plates and the size of the picture reproduction projected is resulted, unlike the contact printing process.
The rayout of the reproduction pictures onto the photosensitive film by the grouping camera requires the precise size of each reproduction picture. When the conventional masking device is used for such a rayout process, a white or a dark line is often appeared between the two reproduction pictures due to an overlap or a gap between the two reproduction pictures, and imparts the fatal damage to the quality of the finished product, particularly in case of a color duplicate film.